Which chili paste/sauce for Phad Kee Mao ?

I have been struggling to make a good Phad Kee Mao. I have looked at quite a few recipes and they typically say soy sauce, oyster sauce and sugar for the "sauce". However I was in a thai restaurant and the menu said it was cooked in chili. When I got the dish, I could see there was a red paste in the dish. The paste was not spicy at all, and was similar in many ways to a tomato paste. Have you worked with chili paste to tell me what kind or brand it might be? I have used Thai chili paste and Thai chili sauce before and this is different...